Get a turkey beater and make a gallon of fresh water with the required chemicals in it. Take about 25-50% out of the cup (get all the poo and crud) and then using the beaker slowly mix the new water in.

Get a turkey beater and make a gallon of fresh water with the required chemicals in it. Take about 25-50% out of the cup (get all the poo and crud) and then using the beaker slowly mix the new water in.